When you've selected an activity to run, click on the "Create Class Code" button.
This will generate a unique class code and a link to view the dashboard. Every new activity will need a new class code in order to start a session. Students cannot start the activity until they have the class code - so sessions can be started days, hours, or mere minutes before you plan to run the activity.
When you're ready to have students start, have them go to student.desmos.com and enter the class code. Although it is not required, we strongly encourage students to sign in with their Desmos accounts. Signing in allows students to resume and view their past activity work.